Saccharomyces yeast hybrids on the rise

Abstract

Saccharomyces hybrid yeasts are receiving increasing attention as a powerful model system to understand adaptation to environmental stress and speciation mechanisms, using experimental evolution and omics techniques. We compiled all genomic resources available from public repositories of the eight recognized Saccharomyces species and their interspecific hybrids. We present the newest numbers on genomes sequenced, assemblies, annotations, and sequencing runs, and an updated species phylogeny using orthogroup inference. While genomic resources are highly skewed towards Saccharomyces cerevisiae, there is a noticeable movement to use wild, recently discovered yeast species in recent years. To illustrate the degree and potential causes of reproductive isolation, we reanalyzed published data on hybrid spore viabilities across the entire genus and tested for the role of genetic, geographic, and ecological divergence within and between species (28 cross types and 371 independent crosses). Hybrid viability generally decreased with parental genetic distance likely due to antirecombination and negative epistasis, but notable exceptions emphasize the importance of strain-specific structural variation and ploidy differences. Surprisingly, the viability of crosses within species varied widely, from near reproductive isolation to near-perfect viability. Geographic and ecological origins of the parents predicted cross viability to an extent, but with certain caveats. Finally, we highlight publication trends in the field and point out areas of special interest, where hybrid yeasts are particularly promising for innovation through research and development, and experimental evolution and fermentation. Take AwayThis article provides (1) a quantitative review of all genomic resources of Saccharomyces yeast species and their hybrids, (2) a compilation of published data on reproductive isolation (spore viabilities) within and between species, (3) highlights and trends in the publication efforts within this field, and (4) areas where yeast hybrids are and will be particularly useful for research and development in the future.

Macroevolutionary diversity of traits and genomes in the model yeast genus Saccharomyces

“…Spore viabilities lower than 1% 71 , 95 in crosses between strains have been considered sufficient to define yeast species using the biological species concept alone. When combined with phylogenetic and ecological species concepts, taxonomic authorities have accepted spore viabilities lower than 10%, as seen for S. eubayanus and S. uvarum , which have the highest AAI values among currently recognized species 96 , 97 .…”

Macroevolutionary diversity of traits and genomes in the model yeast genus Saccharomyces

“…Spore viabilities lower than 1 % 69, 93 in crosses between strains have been considered sufficient to define yeast species using the biological species concept alone. When combined with phylogenetic and ecological species concepts, taxonomic authorities have accepted spore viabilities lower than 10 %, as seen for S. eubayanus and S. uvarum , which have the highest AAI values among currently recognized species 94, 95 .…”

Gene acquisition by giant transposons primes eukaryotes for rapid evolution via horizontal gene transfer

“…Firstly, as we described previously, the Pegasus Starship contains duplicated DNA and has horizontally transferred into P. variotii which is a species in which duplicated DNA is mutated during sexual crosses, thus the required backcrossing cannot have taken place. Secondly, while hybridisation events have been reported between different fungal species to our knowledge in all cases these occur between species within the same genus [99–101]. Paecilomyces and Spiromastigoides belong to separate orders.…”